• Title, Summary, Keyword: mesophase

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Mesophase formation behavior in petroleum residues

  • Kumar, Subhash;Srivastava, Manoj
    • Carbon letters
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    • v.16 no.3
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    • pp.171-182
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    • 2015
  • Mesophase pitch is an important starting material for making a wide spectrum of industrial and advanced carbon products. It is produced by pyrolysis of petroleum residues. In this work, mesophase formation behavior in petroleum residues was studied to prepare environmentally-benign mesophase pitches, and the composition of petroleum residues and its influence on the mesophase formation was investigated. Two petroleum residues, i.e., clarified oil s (CLO-1, CLO-2) obtained from fluid catalytic cracking units of different Indian petroleum refineries, were taken as feed stocks. A third petroleum residue, aromatic extract (AE), was produced by extraction of one of the CLO-1 by using N-methyl pyrrolidone solvent. These petroleum residues were thermally treated at 380℃ to examine their mesophase formation behavior. Mesophase pitches produced as a result of thermal treatment were characterized physico-chemically, as well as by instrumental techniques such as Fourier-transform infrared spectroscopy, nuclear magnetic resonance, X-ray diffraction and thermogravimetry/derivative thermogravimetry. Thermal treatment of these petroleum residues led to formation of a liquid-crystalline phase (mesophase). The mesophase formation behavior in the petroleum residues was analyzed by optical microscopy. Mesophase pitch prepared from CLO-2 exhibited the highest mesophase content (53 vol%) as compared to other mesophase pitches prepared from CLO-1 and AE.

Stabilization of Mesophase Pitch for Carbon/Carbon Composites (탄소/탄소 복합재를 위한 메조페이스 핏치의 안정화)

  • 임연수
    • Journal of the Korean Ceramic Society
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    • v.34 no.8
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    • pp.817-824
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    • 1997
  • Stabilization is a key stage in the production of advanced carbon/carbon composites (ACC) from mesophase pitch, to render the mesophase infusible and the prevention of puffing during the subsequent carbonization. It is generally known that stabilization process as well as properties of mesophase pitch has a great deal of influence on the properties of the resultant ACC. Hence, it is possible to infer the properties of ACC by examing the stabilized mesophase pitch. In this study, extractions by solvents or acidified solvents extraction were carried out from the A-240 petroleum pitch. The extracted pitches were made into mesophase by heat treatments. Oxidative stabilization by air and non-oxidative stabilization by a chemical free radical initiator were performed. When a soluble polymer is fully stabilized, it should become insoluble in solvents. This phenomenon was used to estimated the degree of stabilization. The non-oxygen stabilized mesophase pitch powder was compared with the air stabilized mesophase pitch powder. FTIR provided additional information on the functional groups.

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Preparation and Characterization of Mesophase Pitches as a Matrix Precursor of Carbon Fiber Reinforced Carbon Composite (탄소/탄소 복합재 매트릭스 전구체로서의 메조페이스 핏치의 제조 및 특성에 관한 연구)

  • 정현진;임연수
    • Journal of the Korean Ceramic Society
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    • v.33 no.12
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    • pp.1387-1393
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    • 1996
  • A study on mesophase pitch as a matrix precursor of carbon fiber reinforced carbon (C/C) composite has been recently presented. This study is concerned with the production of mesophase pitch as matrix precursors for C/C composite from coal tar pitch. A commercial coal tar pitch was heat-treated at 25$0^{\circ}C$ for 2 hours to remove low molecular weight fraction from the pitch then increasing the temperature of the pitch to between 350~45$0^{\circ}C$ to produce mesophase pitch. The pitch was continuously stirred during this time and nitrogen gas was continuously bubbled through the pitch. Spherical and bulk mesophases were formed in the pitch after heat-treatment,. Parent and mesophae pitches were characterized by elemental analysis coke yield solubi-lity in tetrahydrofuran and hexane and an optical microscopy to measure the mesiophase content. It was neces-sary to produce C/C composite that a mesophase pitch with about 30-40 vol% mesophase spherulites can be infiltrated into a fiber preform without a filter effect as a matrix precursor conditions. This condition was satisfied with mesophase pitch heat treated at 40$0^{\circ}C$ for 2 hours. The other heat treatment conditions showed the nuclei of mesophase or bulk mesophae which were not satisfied with the matix precursor condition.

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Effects of Borane-Pyridine Complex on Mesophase Formation from Decant Oil

  • Han, Dong-Yun;Moon, Sook-Young;Lim, Yun-Soo
    • Carbon letters
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    • v.5 no.3
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    • pp.113-117
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    • 2004
  • The mesophase pitch was prepared by adding 1~10 wt% of the borane-pyridine complex (BPC) to decant oil. It was prepared in a reactor held at $450^{\circ}C$ for 2 h in $N_2$ atmosphere. The mesophase pitches were analyzed using thermogravimetric analyzer (TGA), melting point apparatus, X-ray diffraction (XRD) and polarized optical microscope. The coke yield, softening point, toluene insoluble, density and content of anisotropy in the mesophase pitches were increased with BPC contents. The XRD profiles did not show any effect of addition of BPC on the formation of mesophase pitch, while the crystallinity of mesophase pitches was increased when the materials were heat treated with boron compound.

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A study on the Condition of Pyrolysis of Coal Tar Pitch to Form the Mesophase as a Matrix Precursor of Carbon/Carbon Composites (탄소/탄소 복합재 매트릭스 전구체인 이방성 메조페이스 형성을 위한 콜타르 핏치의 열분해 조건 연구)

  • 정형진;정윤중;조동환;임연수;김기원
    • Journal of the Korean Ceramic Society
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    • v.34 no.9
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    • pp.963-968
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    • 1997
  • Coal tar pitch was used to study the effect of the pyrolysis conditions to produce mesophase pitch used as a matrix precursor for carbon/carbon composites. The pyrolysis conditions were presented in all cases that the total pressure was 1 atm and the first stage temperature was changed from 25$0^{\circ}C$ to 34$0^{\circ}C$ to remove the low molecular weight compounds in the pitch, and then, heated to 40$0^{\circ}C$ to form anisotropic mesophase as the second stage temperature. The first stage temperature was very affected to form resulting anisotropic mesophase pitch. The resulting mesophase pitches show a significantly increased anisotropic contents upto 30$0^{\circ}C$. However, the contents of mesophase were decreased above 30$0^{\circ}C$. It was the reason that the first stage temperature had been control the number of free radicals to react the aromatic compounds in the pitch to form high molecular weight compound. Therefore, the two stage pyrolysis method could be very effectively used to control various contents of anisotropic polyaromatic mesophase compared to continuous to continuous heating method.

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Meliorate optical textures and mesophase contents by promising approach of deasphalting of petroleum residues

  • Kumar, Subhash;Srivastava, Manoj
    • Journal of Industrial and Engineering Chemistry
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    • v.48
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    • pp.133-141
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    • 2017
  • The aim of this work is to study melioration in mesophase formation behaviour by deasphalting of petroleum residues. Pitches prepared from VRs have undesirable high values of physico-chemical properties as compared to their corresponding DAOs pitches. This is due to presence of high molecular weight asphaltenes molecules in VRs. The optical microscopic images of VR-390-1 and VR-390-2 pitches showed that they have small sized, distorted and agglomerated types of mesophase having mesophase contents (MC) 25 vol% and 22 vol% respectively but deasphalting of these VRs improve the growth and optical texture of mesophase in DAO-390-1 (29 vol%) and DAO-390-2 (35 vol%).

Mechanical Properties of C-type Mesophase Pitch-based Carbon Fibers

  • Ryu, Seung-Kon;Rhee, Bo-Sung;Yang, Xiao Ping;Lu, Yafei
    • Carbon letters
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    • v.1 no.3_4
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    • pp.165-169
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    • 2001
  • The C-type mesophase pitch-based carbon fiber (C-MPCF) was prepared throuch C-type spinnerette and compared the mechanical properties to those of round type mesophase pitch fiber (R-MPCF) and C-type isotropic pitch fiber (C-iPCF). The tensile strength and modulus of C-MPCF were about 18.6% and 35.7% higher than those of R-MPCF. The tensile strength of C-MPCF was 62% higher than that of C-iPCF of the same $8{\mu}m$ thickness because of more linear transverse texture, which could be easily converted to graphitic crystallinity during heat treatment. The torsional rigidity of C-MPCF was 2.37 times higher than that of R-MPCF. The electrical resistivity of C-MPCF was $8{\mu}{\Omega}{\cdot}m$. The C-iPCF shows far lower electrical resistivity than R-iPCF as well as the mesophase carbon fiber because of better alignment of texture to the fiber axis.

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Derivation of Cubic and Hexagonal Mesoporous Silica Films by Spin-coating

  • Pan, Jia-Hong;Lee, Wan-In
    • Bulletin of the Korean Chemical Society
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    • v.26 no.3
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    • pp.418-422
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    • 2005
  • By introducing spin-coating method to the evaporation induced self-assembly (EISA) process, a simple and reproducible route in controlling the mesophase of silica thin films has been developed for the first time in this work. When a comparatively solvent-rich Si-sol (The atomic ratio of TEOS : F127 : HCl : $H_2O$ : EtOH = 1 : 0.006 : 0.2 : 9.2 : 30) was used as coating solution, the mesophase of resultant silica films was selectively controlled by adjusting the spin-on speed. The cubic mesophase has been obtained from the coating at a low rpm, such as 600 rpm, while the 2-D hexagonal mesophase is formed at a high rpm, such as 2,500 rpm. At a medium coating speed, a mixture of cubic and hexagonal mesophase has been found in the fabricated films. The present results confirm that the evaporation rate of volatile components at initial step is critical for the determination of mesopore structures during the EISA process.

Catalytic hydrogenation-assisted preparation of melt spinnable pitches from petroleum residue for making mesophase pitch based carbon fibers

  • Lee, Dong Hun;Choi, Jisu;Oh, Young Se;Kim, Yoong Ahm;Yang, Kap Seung;Ryu, Ho Jin;Kim, Yong Jung
    • Carbon letters
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    • v.24
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    • pp.28-35
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    • 2017
  • We demonstrated an effective way of preparing melt spinnable mesophase pitches via catalytic hydrogenation of petroleum residue (fluidized catalytic cracking-decant oil) and their subsequent thermal soaking. The mesophase pitches thus obtained were analyzed in terms of their viscosity, elemental composition, solubility, molecular weight, softening point and optical texture. We found that zeolite-induced catalytic hydrogenation under high hydrogen pressure contributed to a large variation in the properties of the pitches. As the hydrogen pressure increased, the C/H ratio decreased, and the solubility in n-hexane increased. The mesophase pitch with entirely anisotropic domains of flow texture exhibited good meltspinnability. The mesophase carbon fibers obtained from the catalytically hydrogenated petroleum residue showed moderate mechanical properties.

Rheological Behaviors of Mesophase Pitches Prepared from Coal Tar Pitch as Carbon Fiber Precursor (탄소섬유 원재료로서 콜타르로부터 제조된 메조페이스 핏치의 유변학적 거동)

  • Lee, Young-Seak;Kim, Tae-Jin
    • Applied Chemistry for Engineering
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    • v.10 no.5
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    • pp.690-695
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    • 1999
  • An experimental study for mesophase pitch prepared from coal tar pitch has been carried out to clarify the rheological behaviors in the molten state. The apparent viscosity, shear stress, shear rate, Qunoline insoluble(QI), and softening point(SP) change were investigated especially. The conditions to increase mesophase content during polymerization were heat treatment time of 5 hrs, catalyst concentration of 3% and reaction temperature of $420^{\circ}C$. Apparent viscosity change with increase in temperature of pitches was different according to the heat treatment conditions and apparent viscosity increased with increasing heat treatment temperature, heat treatment time, contents of mesophase, on the contrary, fluidity is decreased. Rheological behavior of molten mesophase pitches at about $270^{\circ}C$ showed Newtonian behavior below $375^{\circ}C$ and non-Newtonian behavior above $270^{\circ}C$, the flow behavior was analyzed with Casson model.

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